In stroke play, if you hit from outside the teeing ground you get a 2 stroke penalty, but in match play you could hit from outside the teeing ground without penalty, but your opponent could require you to replay your stroke.

In stroke play if your ball hits a fellow competitor you play the ball as it lies, but in match play if your ball hits your opponent you get to replay the stroke……if you want.

In stroke play, if you play out of order you will not be penalized, but if you play out of order in match play your opponent can require you to replay your stroke.

If you make a mistake in adding your scores in tournament play such that you thought you shot an 84 but you really shot an 86 you are not penalized, but if you put a score down on any hole that's less than what you really scored and handed in the scorecard with that error that you will be disqualified unless the mistake was because of a penalty you did not know you incurred and then your score will be adjusted by adding the penalty stroke(s) you didn't know you incurred plus a 2 stroke penalty for violation of Rule 6-6d.

If your ball is in a hazard (water or bunker) and a loose impediment is near your ball, you cannot touch that loose impediment except in the making of a stroke. And you can't touch the sand in a bunker or water in the water hazard with your hand or club except in the making of a stroke. A stroke is the forward movement of the club made with the intention of striking at and moving the ball. Therefore, you cannot touch that loose impediment with your back swing. And in those deep pot bunkers, you can't let your club touch the sand on your back swing without incurring a 2 stroke penalty. Remember, a loose impediment is something natural like a leaf or branch that is not fixed to from whatever it grew. Exceptions do exist to the above and it's to your advantage to know them, such as being able to use a club as a cane to prevent falling in the hazard or moving loose impediments or sand in a bunker when searching for your ball.

If your ball makes a pitch mark in the dreaded kikuyu grass that borders the green and spins back a bit, you are not permitted to fix that pitch mark that is not on the green even though you wanted to putt the ball and the pitch mark is on your line of putt. If you do fix that pitch mark you just incurred a 2 stroke penalty. But if your ball made a pitch mark on the green and spun back off the green you are allowed to fix that, and any other, pitch mark on the green even though your ball is not on the green.
That the practice of putting or chipping on the green on which you just completed play is permitted as long as you are not holding up the play of the group behind you. You could also practice putting or chipping on the practice short game area of the course on which you are playing if you don't hold up play. See Rule 7-2.

The Rules of Golf contain many instances where something is a penalty in one form of play, but not in another form of play, or when an action can be a penalty, but then again, may not be a penalty depending on the intent of the player. If you are truly a tournament player you should take the time to review each one of the rules periodically. A complete understanding of them can save you strokes.